All-water supercapacitor enabled by 1-nm clay channels

Water confined to channels one nanometer thick exhibits electrochemical behavior distinct from bulk water, including enhanced protonic conductivity and large dielectric anisotropy. Here, we exploit these characteristics to design a scalable electrochemical energy storage system-a “blue capacitor”-constructed entirely from naturally abundant materials. By assembling layered clays and conductive graphene, we produce 1-nm-thick channels in which confined water acts as the sole electrolyte. We systematically study different clay types, the electrode composition, and separator thickness using complementary physicochemical and electrochemical techniques. The device operates stably up to 1.6 ± 0.1 V, achieves specific capacitances of 40 F g−1, 97 ± 2% coulombic efficiency, and stable performance over more than 60,000 charge-discharge cycles at a voltage window of 1 V and a scan rate of 10 mA. Structural and dynamic analyses validate the device architecture, water purity, and proton transport in the nanopores. These results demonstrate that nanoconfined water can function as an electrolyte in a macroscopic electrochemical device, providing a platform for exploring sustainable aqueous energy storage systems.

DDC Class

621.3: Electrical Engineering, Electronic Engineering

541.37: Electrochemistry

Lizenz

https://creativecommons.org/licenses/by/4.0/

Publication version

publishedVersion

Name

41467_2026_Article_73924.pdf

Type

Main Article

Size

3.87 MB

Format

Adobe PDF

Options

All-water supercapacitor enabled by 1-nm clay channels